Magnetic field sensors are often used to detect position, proximity, or motion of a rotating object. For example, magnetic field sensors are used in automobile transmissions to detect speed of rotation. A magnetic target, such as a toothed gear, can be attached to a rotating element within a transmission. Magnetic field sensing elements are placed where they can detect the teeth of the gear as they rotate past the magnetic field sensing elements. As the gear moves relative to the magnetic field sensing elements, it affects a magnetic field, which is detected by the magnetic field sensing elements. Changes in the magnetic field due to the motion of gear can be detected and processed to produce position, proximity, motion, and/or speed of the gear.
Magnetic field sensors can also be used to detect position of a movable object within an area. For example, magnetic field sensing elements can be placed proximate to an area of interest to detect the position of an object within the area. As the object moves through the area, it may move closer to or further away from the sensors. If the object is close to a sensor, the sensor can detect a strong magnetic field. Conversely, if the object is relatively distant from the sensor, the sensor may pick up a relatively weaker magnetic field.